For example, a flat box such as a box of sweets comprises a box body open at the top and a lid for opening and closing the open top of the box body. The open top of the box body can be closed by putting the lid onto the top of the box body (patent document 1, for example). In the box as disclosed in patent document 1, access to the open top is given by lifting and removing the lid from the box body, and articles can be easily removed from inside the box body through the open top of the box body.